This document presents a peer-to-peer database architecture that uses an ant colony optimization algorithm and semantic support. The architecture was developed to optimize routing queries. Experimental results showed that the approach reduced network traffic without loss of answers received, improving system performance even with increased time to live for messages. The architecture contributes a new search strategy for peer-to-peer databases that is not found in existing literature.

1. Manager: Prof. Dr. Carlos Roberto Valêncio 2011 Grupo de Banco de Dados – IBILCE UNESP – Brazil

2. Architecture for Peer-to-Peer Databases with Routing Queries Using Ant Colony Algorithm and Semantic Support Carlos Roberto Valêncio Leandro Rincon Costa Paulo Scarpelini Neto Adriano Mauro Cansian

3. Topics Introduction Theory Substantiation Correlated works Developed Work Experimental Results Conclusions

4. Introduction In a peer-to-peer system, the nodes which are connected to the network, interact and share resources, services and information. Recent researches have indicated the development of applications which take into account the semantics associated to the data when permitting that richer information be shared in such networks. To find information in a peer-to-peer network is a complex process due to the network’s high flexibility and dynamicity, as well as the absence of a centralised information management. This work presents as an original contribution, a routing system architecture that applies an Ant Colony Optimisation (ACO) algorithm supported by ontologies.

5. Theory Substantiation Peer-to-peer database systems: is made-up of autonomous nodes that share information from their databases and access information belonging to other nodes in the network. Ant Colony Optimisation Algorithm: was inspired on the behaviour of ants in nature, in which they communicate one to another by means of a chemical substance called pheromone, which, among other things, guides them to the best roads to food . That algorithm can be adopted to optimise routing in peer-to-peer networks, to offer routes having a greater possibility of success in returning results. Ontologies: “An explicit and formal specification of a shared conceptualisation”. Can be used to integrate databases, permitting interoperability between said bases, creating a semantic link between the different schema elements.

6. Correlated works Some peer-to-peer database systems have been proposed in literature, namely: Piazza; Xpeer; Hyperion; PeerDB. Among the principal peer-to-peer database systems in literature, none of the architectures use the same search strategy that is presented in this work. Therefore, this work contributes by bringing to the peer-to-peer database area a new architecture for the searching of information based on the flooding technique optimised with the ACO algorithm and supported by ontologies.

7. Developed Work - System architecture To present the proposed functioning of the routing strategy, a peer-to-peer data managing system was created that had the following characteristics: Network architecture – a pure peer-to-peer environment was created, that is, without dedicated servers or super-nodes; Network connection – so that the user be included in the net, he must connect himself to the other users on his list of entry nodes; Search system – for the search, a flooding technique, modified by the application of ACO algorithm concepts, was used; Data classification – for the semantic aggregation to the data with the use of a standard language, a classification based on pre-defined ontologies was used.

8. Developed Work - System architecture

9. Developed Work - Query process Query data process is the principal task done in the system. In a network, with hundreds of thousand searches happening simultaneously, it is expected that innumerable information about good routes to be followed be obtained, enabling a query performance improvement as the time to live (TTL) of the network increases. It possible to reduce the traffic of messages in the network and the time of answers, and so to avoid delays and congestions that may affect system performance.

10. Developed Work - Query process To enable a better understanding about this work, is presents an example of a query to the peer-to-peer database system using the proposed routing strategy. The two different types of ant are illustrated, (a) the explorer ant and in (b) the worker ant.

11. Developed Work - Query process (b) (a) (c) (d)

12. Developed Work - Query process (e) (f) (g) (h)

13. Experimental Results The objective of the tests was to compare the traffic of information in the network, as well as the number of received answers, for each query with the use or not of the Ant Colony Optimisation (ACO) algorithm. Some tests were done to analyse the behaviour of these algorithms when TTL is doubled, since, in a real network, it is impracticable to use a flooding algorithm without a definition of a TTL for the messages. A peer-to-peer network with thirty-two nodes was created for system tests.

14. Comparative graphic of network traffic, where five and ten TTLs were used

15. Comparative graphic of answers received from each query

16. Conclusions This work presents a proposal for a routing architecture in systems of data management in peer-to-peer networks based on Ant Colony Optimisation algorithm and supported by ontologies. This strategy reduces message traffic in the network without a loss of received answers, so a better performance of the systems is obtained, even with a greater TTL definition for the messages. The proposal of this architecture which adopts the presented search strategy is differentiated and not found in literature.

17. Informations: www.gbd.ibilce.unesp.br gbd@ibilce.unesp.br Thank You! 2011 Grupo de Banco de Dados – IBILCE UNESP –Brazil